D.M. Smilgies,Ruipeng Liand M. P. Pileni Nanoscale, 2018, DOI: 10.1039/C8NR04606A
Vicinal Au supracrystal surfaces were prepared from Ausinglesingle domain nanocrystals (NCs) whereas by replacing Ausingleby their polycrystalline counterparts common low-energy supracrystal surfaces are produced. By analogy to atomic crystalline surfaces, we propose a mechanism to explain formation of such unexpected supracrystal vicinal surfaces, composed of only AusingleNCs are non-compact (bctstructure) with coherent alignment of the atomic planes oriented along the  superlattice axis and a slight tilt configuration (8.1°) of NCs. In presence of Co() NCs, these Ausinglesupracrystals loose both the slightly tilted configuration of NCs and their orientational order leading to a superlattice transition from bctto fcc. In contrast, supracrystals of AupolyNCs are unsensitive to the presence of Co() NCs. These intriguing structural changes obtained with Ausinglecompared to Aupolysupracrystals in absence and presence of Co() NCs could explain the formation of vicinal surfaces. Note, the solvent used to disperse the nanocrystals plays a key parameter in the formation of supracrystal vicinal surfaces. Here a new analogy between supracrystals and atomic crystals is presented.